The invention relates to an apparatus for placing a plastic strip around objects and for welding together its overlapping strip portions arranged so as to be displaceable relative to one another to produce heat by a male die mounted in a casing and a female die positioned in a base plate.
Various constructions are known for sealing a plastic to objects by welding, preferably by friction welding. It is common to all these constructions that the overlapping plastic portions are placed between two jaws, called the male die and the female die, after which the jaws are pressed together and moved counter to one another. Due to the movements of the jaws under pressure, the overlapping strip portions are moved against one another so as to soften and partly melt the engaging surfaces of the strip portions in such a way that they form an intimately connected, welded member. The movement of the jaws is brought about in various ways, for example by displacing the overlapping strip portions in the longitudinal direction of the strip (U.S. Pat. Nos. 3,799,835 and 3,984,278) or by a circular movement (U.S. Pat. No. 3,709,758).
The disadvantage of the known constructions is that although they bring about a relatively rapid welding of the overlapping strip portions the construction procedure is relatively complicated and costly and in particular a relatively large number of movable and moved parts are used.